Terahertz Plasmonic Waveguide Based Thin Film Sensor

In this paper, we investigate sensing capabilities of a planar plasmonic terahertz waveguide. The waveguide is comprised of one-dimensional array of periodically arranged subwavelength scale corrugations in the form of rectangular dimples in order to ensure the plasmonic response. The terahertz waveguide transmission is observed for polyimide (as thin film) substance filling the dimples. The refractive index of the polyimide film is varied to examine various sensing parameters such as frequency shift, sensitivity, and figure of merit of the fundamental plasmonic resonance supported by the waveguide. We employ a semianalytical transmission line $LC$ circuit model to elucidate our numerical observations. In efforts to improve sensing characteristics, we also examine sensing capabilities of a plasmonic waveguide having V-shaped corrugations and compare results with that of rectangular dimples. The proposed study could be significant in developing new terahertz sensors with improved sensitivity utilizing the plasmonic waveguides.